Air Quality

DISCUSSION: The purpose of the Environmental Protection Agency's (EPA) Air Quality Index (AQI) is to quickly alert people to general air quality conditions and provide guidance that they may need to limit their exposure to outside air. Specifically, the index takes into account observations of various air pollutants, including near-surface ozone, particulate matter (small and larger particles), carbon monoxide, sulfur dioxide, and nitrogen oxide. A calculation converts the observed concentration of each of the above six pollutants to an AQI value. The pollutant with the highest AQI is associated with the scale above where a smaller AQI value (~25) indicates good air quality that poses little risk. A higher value (up to 500) indicates hazardous conditions even for healthy people.

​As described by Physics Today's Mika McKinnon here, the recent fires in California highlighted several issues with the AQI. First, the AQI doesn't specify which pollutant triggered the value given. The pollutant with the highest concentration is important for determining which groups are most at risk. For example, carbon monoxide is especially dangerous for those with a heart attack risk, while ozone is especially dangerous for the very young and old. Thus, the AQI as given doesn't specify which people are most at risk on a given day. In addition, how frequently the AQI is updated depends on the number of observations in an area. In remote locations with few observations, it can take 24 hours or longer for the AQI to update. In the case of California fires, there was visibly hazy, dangerous air, while the AQI indicated good air quality conditions before it eventually updated to a higher value. Obviously, an AQI that doesn't necessarily match current conditions could pose a problem.

​The point of this article is not to discourage people from paying attention to the AQI. It does provide some indication of air quality conditions and actions that may need to be taken by certain groups of people. It is easy to read and understand. However, it is important to understand the limitations of this tool in order to use it most effectively and to spur further improvements of the tool.

DISCUSSION: Although the excessive heat of the summer months allows for beach days, BBQs, and playing outside, it is crucial to remain aware of the extraordinarily hot temperatures for health concerns. The relentless sunshine can create unsafe air quality conditions in many regions across the United States. Not only is it essential to remain aware of summer illnesses like heat stroke, but an extra precaution must be taken during the excruciating summer weather to avoid respiratory and cardiovascular problems related to unsafe air quality. Specifically, tropospheric ozone forms as a result of sunlight reacting with nitrous oxides and volatile organic compounds. Therefore, the longer the sun shines throughout the day, the poorer the air can become. Sensitive groups are at severe risk during the summer, especially in densely populated/urban areas due to heightened emissions. Poor air quality is responsible for lung injury and possesses life-threatening outcomes. It is imperative to bear in mind that one should always attempt to lessen car emissions by consolidating trips, reduce the use of substances with chemical solvents, and to check air quality updates. The National Weather Service, partnered with the Environmental Protection Agency, produces daily air quality forecasts to protect the safety of people and the environment, so be sure to keep updated on your region’s ozone and smoke outlooks! A helpful resource for air quality is the EPA’s AirNow, which utilizes the AQI Index and is an easy-to-use tool to remain informed when it is (and when it is not) safe to spend time outdoors!

According to models published in the Journal of Geophysical Research: Atmospheres, a decrease in sulfur dioxide levels in the United States can markedly increase the rainfall of Africa’s Sahel region by the year 2100.

Since the 1970’s, the United States has been on a mission to particularly cut emissions of sulfur dioxide. Sulfur dioxide is a harmful gas that is yielded from the burning of coal. This gas leads to acid rain, poisoning crops around the world, and even induces respiratory problems in animals. In addition, sulfur dioxide “simultaneously cools and dries earth's climate by reflecting sunlight back to space and suppressing heat-driven evaporation near the ground.” By eliminating sulfur dioxide emissions out completely, models suggest that by the year 2100, there will be a 10% increase (from 2000 levels) in rainfall in Africa’s Sahel region (the transition region between the Sahara desert to the north and the Savanna to the south).

The increase in rainfall will also cause the crop season to last longer, allowing harvesting to hit an all-time high. This will also generate economic growth.

DISCUSSION: As another neat scientific expedition being funded by the National Oceanic and Atmospheric Administration (NOAA) gets underway, here is a neat graphic and discussion below concerning this particular air pollution-oriented project. The project's name being the "Atmospheric Tomography mission" has it's goals set on studying and developing an improved understanding for how relatively short-lived greenhouse gases (e.g., ozone, methane, etc.) ultimately contribute to the effects of climate change around the world. Attached below you can clearly see the NOAA DC-8 aircraft being prepared for its departure! A very neat study without question! To learn about other neat studies being done in regards to air pollution and/or air quality research around the world, be sure to click here!